li {
    list-style: none;
}

.preview_wrap {
    width: 451px;
    height: 590px;
}

.preview_img {
    position: relative;
    height: 450px;
    background-color: pink;
    border: 1px solid #ccc;
}

.mask {
    display: none;
    position: absolute;
    top: 0;
    left: 0;
    width: 300px;
    height: 300px;
    background: #FEDE4F;
    /* 半透明 */
    opacity: .5;
    border: 1px solid #ccc;
    cursor: move;
}

.big {
    display: none;
    position: absolute;
    left: 450px;
    top: 0;
    width: 510px;
    height: 510px;
    background-color: pink;
    z-index: 999;
    border: 1px solid #ccc;
    overflow: hidden;
}

.big img {
    position: absolute;
    top: 0;
    left: 0;
}

.preview_list {
    position: relative;
    height: 60px;
    margin-top: 10px;
    overflow: hidden;
}

.list_item {
    position: absolute;
    width: 800px;
    height: 60px;
    margin: 0 auto;
    transition: .4s ease-in-out;
}

.list_item li {
    float: left;
    width: 56px;
    height: 56px;
    border: 2px solid transparent;
    margin: 0 10px;
}

.list_item li:nth-child(1) {
    margin-left: -5px;
}

.list_item li:nth-child(5) {
    margin-right: 30px;
}

.list_item li.current {
    border-color: #c81623;
}

.arrow_prev,
.arrow_next {
    position: absolute;
    top: 15px;
    width: 22px;
    height: 32px;
    background-color: purple;
    z-index: 2;
}

.arrow_prev {
    left: 0;
    background: url(../images/arrow-prev.png) no-repeat;
}

.arrow_next {
    right: 0;
    background: url(../images/arrow-next.png) no-repeat;
}